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Considerations for realistic ECCS evaluation methodology for LWRs
This paper identifies the various phenomena which govern the course of large and small break LOCAs in LWRs, and affect the key parameters such as Peak Clad Temperature (PCT) and timing of the end of blowdown, beginning of reflood, PCT, and complete quench. A review of the best-estimate models and correlations for these phenomena in the current literature has been presented. Finally, a set of models have been recommended which may be incorporated in a present best-estimate code such as TRAC or RELAP5 in order to develop a realistic ECCS evaluation methodology for future LWRs and have also been compared with the requirements of current ECCS evaluation methodology as outlined in Appendix K of 10CFR50. 58 refs
A Long-Term MAAP 3.0B Analysis of a Severe Anticipated Transient Without Scram Accident in a Boiling Water Reactor
En Face Optical Coherence Tomography and Optical Coherence Tomography Angiography of Multiple Evanescent White Dot Syndrome : New Insights Into Pathogenesis
PURPOSE:: To localize the various levels of abnormalities in multiple evanescent white dot syndrome by comparing \u201cen face\u201d optical coherence tomography (OCT) and OCT angiography with various conventional imaging modalities. METHODS:: In this retrospective case series, multimodal imaging was performed in 9 retinal centers on 36 patients with multiple evanescent white dot syndrome and included widefield fundus autofluorescence (FAF), fluorescein angiography (FA), and indocyanine green angiography, and B-scan and \u201cen face\u201d C-scan enhanced depth imaging and spectral domain OCT. Optical coherence tomography angiography was also performed at the level of the superficial and deep retinal capillary plexus and choroid. RESULTS:: Multiple evanescent white dot syndrome lesions were more numerous and more easily detectable with FA and FAF. Two types of lesions were identified with FAF, FA, and indocyanine green angiography: larger widely scattered \u201cspots\u201d (approximately 200 \u3bc in diameter) that were hyperfluorescent with FA, hyperautofluorescent with FAF, and hyporeflective in indocyanine green angiography, representing abnormalities primarily at the retinal pigment epithelium/photoreceptor junction; and punctate \u201cdots\u201d (less than 100 \u3bc in diameter) that were hyperfluorescent with FA, hyperautofluorescent, or isoautofluorescent with FAF, and hypofluorescent with indocyanine green angiography and that localized to the outer nuclear layer. These lesions colocalized with \u201cen face\u201d OCT. The larger confluent \u201cspots\u201d were hyporeflective and colocalized to the level of the ellipsoid zone, whereas smaller hyperreflective \u201cdots\u201d colocalized to the outer nuclear layer. The location of the \u201cdots\u201d in the outer nuclear layer was further confirmed by structural spectral domain optical coherence tomography which showed coalescence of the dots into hyperreflective lines extending from the external limiting membrane to the outer plexiform layer in certain cases. Optical coherence tomography angiography analysis of the retinal microvasculature and choriocapillaris and choroid were entirely unremarkable in 100% of our patients. CONCLUSION:: By combining multimodal imaging, the authors propose that multiple evanescent white dot syndrome is primarily the result of inflammation at the outer photoreceptor level leading to a \u201cphotoreceptoritis\u201d and causing loss of the inner and outer segments. Its evanescent nature suggests that the photoreceptor cell bodies remain intact ensuring complete recovery of the photoreceptor inner and outer segments in most cases, compatible with the clinical course of spontaneous resolution of white spots and dots